From time to time people speculate whether Einstein was an atheist. Richard Dawkins, for example, said in his book The God Delusion that Einstein was an atheist. However, Einstein addressed this point directly:
I am not an atheist, and I don’t think I can call myself a pantheist.
This quote comes from There Is a God by Anthony Flew. Flew in turn credits Max Jammer’s book Einstein and Religion, page 44.
For sixty years Anthony Flew was an apologist for atheism. Four years ago he announced that he had changed is mind. Last year he published There Is a God, an account of how he first became an atheist and of how decades later he reversed his position.
Einstein was an atheist. I documented this in my new blog Einstein the Atheist.
http://einsteintheatheist.blogspot.com/
Going directly to Einstein’s writings seems to be the only possible way to understand with any subtlety how he thought on this question. In “The World As I See It” (a collection of articles by Einstein), there is an essay “Religion and Science” that paints a picture of his views on religion. That essay is available online here.
Depending on one’s specific sense of what atheism is, I could see Einstein described as atheist or not. In the sense that Einstein saw atheism, it seems clear he did not want to be identified as such.
But he also knew his views could fairly be labeled as atheist from other perspectives.
So there you have it. He isn’t and he is! My feeling is that either “answer” to the question “Was Einstein an Atheist?” can’t capture Einstein’s religious philosophy.
By the way, I pulled these two Einstein quotes from the wikipedia page Religious view of Albert Einstein, which looks well developed. It even has the quote from this post, “I am not an atheist”, in a wider context.